Circadian rhythms of body temperature and metabolic rate in naked mole-rats

Body temperature (T-b) and metabolic rate (O-2 consumption) were measured c ontinuously in naked mole-rats. Circadian rhythms were observed for both pa rameters. Body temperature increased at the end of the light phase in a 12L :12D cycle in three of four animals. The remaining animal exhibited a freer unning rhythm of T-b When animals had access to running wheels, the time of elevated T-b coincided closely with the time of increased running wheel ac tivity. Rhythms of T-b continued following removal of the wheels, but the d uration of increased T-b was decreased as compared to the duration of T-b e levation in the presence of wheels. Metabolic rate was increased at the sam e circadian phase as the increase in T-b and running wheel activity. These observations extend our earlier findings on circadian rhythms of locomotor activity in naked mole-rats and suggest that the circadian system may have significant physiological functions in this subterranean rodent. (C) 2000 E lsevier Science Inc. All rights reserved.